|Publication number||US5629648 A|
|Application number||US 08/697,897|
|Publication date||May 13, 1997|
|Filing date||Aug 30, 1996|
|Priority date||Mar 29, 1995|
|Also published as||US5608353|
|Publication number||08697897, 697897, US 5629648 A, US 5629648A, US-A-5629648, US5629648 A, US5629648A|
|Inventors||William J. Pratt|
|Original Assignee||Rf Micro Devices, Inc.|
|Export Citation||BiBTeX, EndNote, RefMan|
|Patent Citations (13), Referenced by (151), Classifications (14), Legal Events (8)|
|External Links: USPTO, USPTO Assignment, Espacenet|
This application is a continuation of application Ser. No. 08/412,667, filed. Mar. 29, 1995, pending.
1. Field of the Invention
The present invention generally relates to monolithic radio frequency (RF) microwave integrated circuits, and more specifically to a multiple device structure used for RF power amplifications using a heterojunction bipolar transistor (HBT).
2. Description of the Related Art
Heterojunction bipolar transistors enable more efficient RF power amplification than other semiconductor devices in integrated circuit form. Extremely high power added efficiency can be obtained because of the high power density and high breakdown of the HBT devices. For high power designs, a multitude of devices are used in some form of parallel structure in order to distribute the power over a sufficient area such that excessive heating is not present to degrade the performance or reliability of the devices.
During normal operation, the current is equally distributed through the many HBTs and excessive heat and other problems do not result. However, if the HBTs are even slightly mismatched, one HBT will operate at a higher temperature than the others and draw a larger amount of current. Since the combined current of all devices is much more than enough to cause destruction of the hot HBT, the possibility exists for what is called in the art, "thermal runaway." Thermal runaway results when one device fails, causing a chain reaction failure of other components. Unfortunately, small differences in devices or placement can cause an imbalance of heating between the individual devices. Any bipolar device which is connected in parallel with other similar devices and which is hotter than its neighbors will tend to draw more current, thus heating itself even more. The heating compounds itself and the result is a thermal runaway phenomenon which will destroy the device and the integrated circuit (IC) itself.
Two prior art circuit techniques which attempt to avoid this problem are the use of an emitter ballast resistor (FIG. 2), and the use of cascode device cells (FIG. 3). In FIG. 2, the ballast resistors degenerate the gain of the device such that increased collector current tends to increase emitter voltage and thereby decrease the emitter-base bias voltage, hence reducing current. A thermally stable circuit can be achieved by making the emitter ballast resistors sufficiently large to prevent this degeneration.
Another method is to use cascode devices as shown in FIG. 3. In this circuit, most of the voltage is impressed on the upper (common base) transistor in each pair. Therefore, most of the heat is generated in this device instead of the common emitter amplifier, which can now operate at a much lower temperature and thereby minimizing the possibility of thermal runaway.
The prior art designs, however, contain limits on efficiency. In the above circuits, other devices are used to achieve thermal stability which are placed in series with the output device. It is desired that as much power taken from the DC power supply as possible is transformed into RF power at the output of the circuit. Any power consumed in the circuit itself, therefore, is wasted and results in degraded overall efficiency. In FIG. 2, the DC and AC collector current that drives the output must pass through the emitter ballast resistors. Therefore, significant power is dissipated in those resistors. This translates to wasted power, and hence reduced efficiency of the amplifier. Since gallium arsenide generally is not a good heat conductor, the emitter ballast resistors have to be quite large to thermally stabilize the circuit and the efficiency loss is commensurably large.
In a cascode circuit (FIG. 3), another transistor is placed in series with the output. The effect is the same as above, i.e., the extra transistor consumes power hence reducing efficiency. The efficiency loss is quite severe because the common emitter's collector must be maintained at a fairly high voltage (one volt or more) in order for that transistor to stay out of saturation that would reduce gain and linearity. Therefore, the cascode arrangement is inferior to the emitter ballast method from a thermal stability point of view.
Thus there is a need in the art for an efficient and linear amplifier which can be built in HBT integrated circuit technology.
The present invention generally relates to an improved heterojunction bipolar transistor power amplifier circuit providing an efficient and linear amplifier comprising: a first heterojunction bipolar transistor (HBT) having a base emitter voltage; a power supply; a power supply resistor connected to the power supply causing DC current to flow through the first HBT which develops a resultant voltage equal to the base emitter voltage of the first HBT; at least two manifold base resistors; at least two output HBTs, each of which receive the resultant voltage through its corresponding manifold base resistor; a RF signal input; at least two segmented capacitors, each coupled in parallel to receive the RF signal input and to the input of each corresponding output HBT; the,segmented capacitors having a common input connected to the RF signal input and having individual outputs that are DC isolated from each other and which are connected to each output HBT; a RF output signal obtained, from the parallel connection of the output HBTs; and provided that each HBT is connected to ground.
These and other aspects of the present invention as disclosed herein will become apparent to those skilled in the art after a reading of the following description of the preferred embodiments when considered with the drawings.
FIG. 1 is a prior art electrical schematic of a conventional single transistor amplifier showing a commonly used base biasing scheme.
FIG. 2 is a prior art electrical schematic of a multiple device design that uses emitter ballast resistors to achieve thermal stability.
FIG. 3 is a prior art electrical schematic of a multiple device cascode amplifier.
FIG. 4 is an electrical schematic of a multiple device amplifier disclosing an embodiment of the present invention.
FIG. 5 is an electrical schematic of a multiple device amplifier optimized for linearity that uses emitter follower bias circuit.
FIG. 6 is a drawing of a segmented capacitor.
The drawings are for the purpose of describing a preferred embodiment of the invention and are not intended to limit the present invention.
As used herein, efficiency is generally defined to be Power Added efficiency--Total RF Power OUT divided by total RF plus DC power IN. Symbols used in the figures are as follows:
Any element with a label which has the prefix "R" or has the resistor symbol is a resistor.
Any element with a label Which has the prefix "C" is a capacitor.
Any element with a label which has the prefix "L" is an inductor.
Any element with a label which has the prefix "Q" is an HBT (Heterojunction Bipolar Transistor).
The label "RFIN" refers to the input signal port of the amplifier.
The label "RFOUT" refers to the output signal port of the amplifier.
The label "VCC" refers to the power supply input connection.
The "Ground" symbol refers to both signal and Power Supply common connection.
The "Battery" symbol refers to a source of DC voltage.
In FIG. 1, Q1 is the power amplifier transistor. It has an emitter ballast resistor (RBALLAST) connected between the emitter of the transistor and ground. The emitter current flows through this resistor and as the current increases, the voltage at the emitter of Q1 becomes more positive which, in turn, decreases the voltage between the base (which has a fixed DC voltage) and emitter of the device causing less current to flow. Hence, the ballast resistor causes negative feedback and provides thermal stability of the device.
The bis network consists of Q8, and RB. The resistor R0 connected to VCC causes DC current to flow through Q8, which develops a voltage equal to the VBE of the transistor. This voltage is fed to the base of Q1 through RB, causing similar flow of current through Q1.
Capacitor C1 connects the RF input port of the amplifier to the base of Q1, coupling RF (but not DC) voltage to the base of Q1.
The output of the amplifier is taken from the collector of Q1.
In FIG. 2, the circuit is the equivalent of the amplifier shown in FIG. 1, except that an array of individually smaller transistors (Q1A . . . Q1N) are used in place of the larger single transistor of FIG. 1. Each individual transistor has its own ballast resistor (RBALLAST) connected between the emitter of each transistor and ground such that each individual transistor is thermally stabilized. The base bias voltage generated by Q8 is coupled to all transistors in parallel through resistor RB. The output is taken from the parallel connection of all collectors.
In FIG. 3, a "Cascode" arrangement for the output stage of the amplifier is shown. Here, each parallel output device is actually two transistors (e.g., Q1A, Q1B and Q2A, Q2B). The lower transistor (B) has RF drive (coupled through C1 from the RFIN port) and DC bias (through RB) applied to the base as in FIG. 2. Base bias voltage is developed as described for FIG. 1. The emitters of the lower transistors are grounded, however, with no ballast resistor. The upper transistor (A) has its emitter connected to the collector of the lower transistor (B). The output is taken from the parallel connections of the upper transistors. DC base voltage to the upper transistor is supplied from the battery. This circuit is thermally stable because the collector voltage of the lower transistor is at a very low value (battery voltage minus the VBE, drop of the upper transistor) rather than the full VCC voltage for the common emitter amplifier. Therefore, even though the current may be high, power consumption (and thus heating) in the lower transistor (which sets the current level) is low because of the low collector voltage (Power=Voltage×Current). The upper transistor (A) becomes quite hot since the full power is impressed, but that transistor does not control current, so no thermal runaway is present.
FIG. 4 shows a preferred embodiment of the new circuit.
The bias network consists of Q8, and manifold base resistors--once for each transistor (RBI . . . RBN). The resistor connected to VCC causes DC current to flow through Q8, which develops a voltage equal to the VBE of the transistor. This voltage is fed to the base of each output transistor (Q1A . . . Q1N) through individual base resistors (RBI . . . RBN), causing a similar flow of current through each Q1 transistor.
The RF signal from the input port (RFIN) is coupled to each transistor through the segmented capacitor C1. Capacitor C1 has a common input connected to RFIN and individual outputs which are DC isolated from each other and which are connected to each output transistor base. The capacitor is schematically represented as an array of capacitors (C1A . . . C1N).
The output transistors have no ballast resistors, but instead, are connected directly to ground. The output is taken from the parallel connection of the collectors of Q1A through Q1N.
This configuration is thermally stable because increased heating in the output transistors causes the BETA (Collector Current divided by Base current) to be reduced, hence requiring more base current to maintain a given collector current. Thus, as the transistors become hotter, base current increases, causing a larger voltage drop across each base resistor (RB1 . . . RBN), which, in turn, reduces VBE (base to emitter voltage). This reduction in VBE reduces collector current, providing negative feedback, hence providing thermal stability.
FIG. 5 shows a preferred embodiment of the new circuit that enhances amplification linearity. The operation of the output stage consisting of C1A through C1N, RB1 through RBN, and transistors Q1A through Q1N is the same as that of FIG. 4.
The bias circuit is different in that it provides a low impedance, linear bias supply for the output stage which enhances amplification linearity of the circuit. The bias voltage is derived from two diode connected transistors (Q7 and Q8). The resistor connected to VCC provides current to these devices which are connected in series. The voltage at the collector of Q7 is two times VBE. This voltage is impressed on the base of Q9, the emitter follower transistor. The collector of Q9 is connected to VCC. The emitter voltage is the base voltage minus VBE. Therefore, since the transistors are identical, the emitter voltage of Q9 is equal to VBE (2×VBE-VBE=VBE). This is the desired bias voltage for the output transistors Q1A through Q1N. An emitter resistor is placed in between the emitter of Q9 and ground in order to force a static collector current through Q9 even when the current demand from the output transistors is low. This is done to maintain a low impedance at the emitter of Q9.
Inductor L1 is optional. If not present, the emitter of Q9 is connected to each RB resistor to provide base bias for the output transistors. Linearity is improved because the bias supply at Q9 emitter is nearly an ideal voltage source. Addition of inductor L1 improves linearity still further because it reduces the RF signal power which is coupled back to the bias supply source. This means that the collector current of Q9 is only DC without RF current, making that transistor more linear. FIG. 6 shows a pictorial representation of the segmented capacitor. In an integrated circuit, connections are made between various elements (resistors, capacitors, transistors, etc.) using metal traces on the surface of the chip. Two layers of metal interconnect are commonly used and one layer (top metal--M2) may cross over the other layer (bottom layer--M1). These layers are isolated by a thin layer of insulator material so that they do not form an electrical short circuit to one another. In the figure, the top metal layer is shown as dotted lines while the bottom layer is shown as solid lines.
In the segmented capacitor, the RFIN port is connected to the bottom metal layer. This metal feature is large and is spread over the entire area of the capacitor. Individual smaller top metal features are placed over (on top of) the bottom layer as shown with the dotted lines in the figure. Since the insulation between layers is thin, a two plate capacitor is formed wherever the top layer overlaps the bottom layer. The capacitance is determined by the area of the overlap. The top metal features are extended beyond the capacitor area (right side of drawing), so that each top metal feature may be used to connect to an individual transistor base. Hence the base of each transistor is AC connected to the RFIN port through a capacitor, while they remain isolated for DC voltages.
Many physical layouts for the segmented capacitor are possible and need not be rectangular as shown. Also, the bottom and top layers may be interchanged. The feature of this device is the fact that it has one common input node and manifold output nodes formed by segmenting one of the metal layers of the device.
In accordance with this invention, no elements, either resistors or other transistors, are placed in series with other output devices. All DC input power from the power supply is transformed into RF power at the output with the exception of the unavoidable loss in the HBT output devices, themselves. This translates to the maximum possible efficiency.
Thermal stabilization is optimized in the improved circuit disclosed herein. The collector current of each HBT device is proportional to the base emitter voltage (VBE), which is the voltage difference between the base of the device and the emitter of the device. This voltage, VBE, for a given collector current goes down as temperature rises. Therefore, thermal instability results if the base emitter voltage (VBE) remains constant. If temperature goes up, collector current goes up, thereby increasing the power and heating in the device. This, in turn, causes the VBE to be reduced for a given current, and since VBE is constant, increased current and heating continue unabated until the device is destroyed.
Thermal stability is achieved in this design by taking advantage of a consistent characteristic of HBT transistors; co namely, that DC Beta (Collector current divided by Base current) decreases as junction temperature goes up. Therefore, as a device heats up, its base current goes up accordingly, assuming a constant collector current. Conversely, if base current remains constant, collector current is reduced. Placing a resistance in series with the base of each devices achieves thermal stability because (assuming a constant output power and collector current), as the device becomes warmer, base current must increase to counter the reduced Beta of the device. In the circuit implementation, the value of the base resistor is set to offset the decreasing VBE to yield the desired collector current. That is, the increasing base current multiplied by the base resistor value (IR drop) gives an increased voltage drop which compensates for the VBE shift attendant to higher temperature, thus achieving thermal stability.
Since each of the many devices used to make up a complete power amplifier are almost thermally independent in a Gallium Arsenide process (which is used for HBT), each device must have its own thermal stabilization. That is, for each device, a base resistor is needed. Driving the many bases through the base resistors would reduce the gain of the amplifier significantly since much of the RF input power from the driver would be dissipated in the base resistors. Since it is necessary to drive all devices in parallel, this invention includes in a preferred embodiment the use of a segmented capacitor which is shown in FIG. 6 and which allows each base to be isolated for thermal stability purposes, but all connected together at the RF frequency. This circuit element is similar in construction to a standard Metal-Insulator-Metal (MIM) capacitor except that the top (or bottom) metal is segmented to provide DC isolation of each HBT base connection. That is, the capacitor provides a common AC (RF signal) connection between all device bases, but keeps them isolated at DC.
An HBT power amplifier designed in accordance with this invention has achieved better efficiency performance than previous art designs that have been reported. In one test, utilizing a preferred embodiment, a chip was fabricated using a Gallium Arsenide HBT process. The final power amplifier (FPA) employed an array of twenty-six 2 um×10 um quad emitters, dual collector transistors along with 26 base resistors (each 400 Ohms), and a segmented capacitor with a total value of 9.36 pF--each segment is 0.36 pF. The part was housed in a 16 pin plastic SOIC package, known to those skilled in the art. The packaged part was mounted on a test circuit board (printed circuit board) which contained external components for the power supply feed to the output circuit, and a matching network to match the device impedance to 50 Ohms for test purposes. The power loss in these external networks was found to be 5% of the total output power. More specifically, the test results are shown in the table below:
______________________________________TEST RESULTSPARAMETER RESULTS______________________________________Measured Power Output 1.26 Watts (+31 dBm)(including external component loss)Device Power Output 1.323 Watts (taking out external component loss)Current Consumption (Total) .41 AmpsOverall Efficiency 64%Overall Device Efficiency 67%FPA Only Current .365 AmpsFPA Efficiency 75.5%______________________________________
The test conditions were as follows: VCC=4.8 VDC; Input Power=+5 dBm; Frequency=840 MHz.
As is set forth above, this invention takes advantage of the characteristics and ability of the HBT in a way that allows the most efficient and most linear amplifier which can be built in HBT IC technology.
The above description of the preferred embodiments thus detail many ways in which the present invention can provide its intended purposes. While several preferred embodiments are described in detail hereinabove, it is apparent that various changes might be made without departing from the scope of the invention, which is set forth in the accompanying claims.
|Cited Patent||Filing date||Publication date||Applicant||Title|
|US3577092 *||Jul 9, 1968||May 4, 1971||Collins Radio Co||Signal path series step-biased multidevice high-efficiency amplifier|
|US3969752 *||Mar 3, 1975||Jul 13, 1976||Power Hybrids, Inc.||Hybrid transistor|
|US3986058 *||Nov 26, 1975||Oct 12, 1976||Sony Corporation||Transistor biasing circuit|
|US4124823 *||Nov 8, 1976||Nov 7, 1978||Rca Corporation||Microwave coupler|
|US4631495 *||May 6, 1985||Dec 23, 1986||General Electric Company||Low-noise RF preamplifier (especially for nuclear magnetic resonance system)|
|US4728902 *||Sep 8, 1986||Mar 1, 1988||Vtc Incorporated||Stabilized cascode amplifier|
|US5066926 *||Jun 26, 1990||Nov 19, 1991||Pacific Monolithics||Segmented cascode HBT for microwave-frequency power amplifiers|
|US5109262 *||Aug 10, 1990||Apr 28, 1992||Nec Corporation||Bipolar transistor with reduced collector resistance|
|US5214394 *||Apr 15, 1991||May 25, 1993||Rockwell International Corporation||High efficiency bi-directional spatial power combiner amplifier|
|US5233310 *||Jun 29, 1992||Aug 3, 1993||Mitsubishi Denki Kabushiki Kaisha||Microwave integrated circuit|
|US5274342 *||Feb 28, 1992||Dec 28, 1993||Hughes Aircraft Company||Microwave monolithic integrated circuit (MMIC) including distributed cascode bipolar transistor amplifier unit|
|US5352911 *||Oct 28, 1991||Oct 4, 1994||Trw Inc.||Dual base HBT|
|US5422522 *||Aug 20, 1992||Jun 6, 1995||Sgs-Thomson Microelectronics, Inc.||Device for biasing an RF device operating in quasi-linear modes with temperature compensation|
|Citing Patent||Filing date||Publication date||Applicant||Title|
|US5821602 *||Nov 25, 1996||Oct 13, 1998||Spectrian, Inc.||RF power transistor having improved stability and gain|
|US5869381 *||Sep 29, 1997||Feb 9, 1999||Spectrian, Inc.||RF power transistor having improved stability and gain|
|US6046641 *||Jul 22, 1998||Apr 4, 2000||Eni Technologies, Inc.||Parallel HV MOSFET high power stable amplifier|
|US6191656||Jul 23, 1999||Feb 20, 2001||Rf Micro Devices, Inc.||High efficiency, unilateral dual stage RF amplifier|
|US6259324||Jun 23, 2000||Jul 10, 2001||International Business Machines Corporation||Active bias network circuit for radio frequency amplifier|
|US6265943||Jan 27, 2000||Jul 24, 2001||Rf Micro Devices, Inc.||Integrated RF power sensor that compensates for bias changes|
|US6288608||Apr 28, 2000||Sep 11, 2001||International Business Machines Corporation||Radio frequency power amplifier for a battery powered handset unit of a wireless communications system|
|US6307364||Aug 27, 1999||Oct 23, 2001||Rf Micro Devices, Inc.||Power sensor for RF power amplifier|
|US6313712||Jun 13, 2000||Nov 6, 2001||International Business Machines Corporation||Low power crystal oscillator having improved long term and short term stability|
|US6329809||Jan 27, 2000||Dec 11, 2001||Rf Micro Devices, Inc.||RF power amplifier output power sensor|
|US6373339||Jun 14, 2001||Apr 16, 2002||International Business Machines Corporation||Active bias network circuit for radio frequency amplifier|
|US6448858||Sep 15, 2000||Sep 10, 2002||International Business Machines Corporation||Mask layout for sidefed RF power amplifier|
|US6448859||Mar 27, 2001||Sep 10, 2002||Kabushiki Kaisha Toshiba||High frequency power amplifier having a bipolar transistor|
|US6492874||Jul 30, 2001||Dec 10, 2002||Motorola, Inc.||Active bias circuit|
|US6528983||Nov 2, 2001||Mar 4, 2003||Rf Micro Devices, Inc.||Power sensor for RF power amplifier|
|US6549076||Sep 24, 2001||Apr 15, 2003||Kabushiki Kaisha Toshiba||High-output amplifier|
|US6624702||Apr 5, 2002||Sep 23, 2003||Rf Micro Devices, Inc.||Automatic Vcc control for optimum power amplifier efficiency|
|US6661290||Jan 18, 2002||Dec 9, 2003||Kabushiki Kaisha Toshiba||High-frequency power amplifier|
|US6678513||May 31, 2001||Jan 13, 2004||Skyworks Solutions, Inc.||Non-linear transistor circuits with thermal stability|
|US6686801||Jul 23, 2002||Feb 3, 2004||Mediatek Inc.||Power amplifier with distributed capacitor|
|US6707341 *||Jul 11, 2001||Mar 16, 2004||Renesas Technology Corp.||Semiconductor device with bipolar transistor device|
|US6727761 *||Sep 3, 2002||Apr 27, 2004||Triquint Semiconductor, Inc.||Resonant bypassed base ballast circuit|
|US6753734||Feb 4, 2003||Jun 22, 2004||Anadigics, Inc.||Multi-mode amplifier bias circuit|
|US6775525 *||Oct 26, 2000||Aug 10, 2004||Renesas Technology Corporation||Radio communication apparatus and semiconductor device|
|US6784747||Mar 20, 2003||Aug 31, 2004||Analog Devices, Inc.||Amplifier circuit|
|US6803643||Sep 30, 2002||Oct 12, 2004||M/A-Com, Inc.||Compact non-linear HBT array|
|US6816015 *||Mar 27, 2003||Nov 9, 2004||Analog Devices, Inc.||Amplifier circuit having a plurality of first and second base resistors|
|US6822517||Jan 9, 2004||Nov 23, 2004||Renesas Technology Corp.||Power amplifier module|
|US6828861||Aug 7, 2003||Dec 7, 2004||Mediatek Incorporation||Power amplifier with distributed capacitor|
|US6831506||Sep 17, 2003||Dec 14, 2004||Rf Micro Devices, Inc.||Reconfigurable filter architecture|
|US6842075||Dec 13, 2002||Jan 11, 2005||Anadigics, Inc.||Gain block with stable internal bias from low-voltage power supply|
|US6903606||Aug 25, 2003||Jun 7, 2005||Rf Micro Devices, Inc.||DC offset correction using unused LNA|
|US6906584||Dec 10, 2003||Jun 14, 2005||Rf Micro Devices, Inc.||Switchable gain amplifier having a high-pass filter pole|
|US6969978||Mar 17, 2003||Nov 29, 2005||Rf Micro Devices, Inc.||DC-DC converter with reduced electromagnetic interference|
|US6970040||Nov 13, 2003||Nov 29, 2005||Rf Micro Devices, Inc.||Multi-mode/multi-band power amplifier|
|US6972658||Nov 10, 2003||Dec 6, 2005||Rf Micro Devices, Inc.||Differential inductor design for high self-resonance frequency|
|US6980039||Mar 3, 2004||Dec 27, 2005||Rf Micro Devices, Inc.||DC-DC converter with noise spreading to meet spectral mask requirements|
|US6989712||Mar 17, 2004||Jan 24, 2006||Triquint Semiconductor, Inc.||Accurate power detection for a multi-stage amplifier|
|US6998919||Oct 22, 2003||Feb 14, 2006||Rf Micro Devices, Inc.||Temperature compensated power amplifier power control|
|US7002391||Mar 27, 2003||Feb 21, 2006||Rf Micro Devices, Inc.||Selectable input attenuation|
|US7010284||Jun 10, 2003||Mar 7, 2006||Triquint Semiconductor, Inc.||Wireless communications device including power detector circuit coupled to sample signal at interior node of amplifier|
|US7015761||Oct 29, 2004||Mar 21, 2006||Renesas Technology Corp.||Power amplifier module|
|US7026665||Oct 20, 2003||Apr 11, 2006||Rf Micro Devices, Inc.||High voltage GaN-based transistor structure|
|US7033961||Jul 15, 2003||Apr 25, 2006||Rf Micro Devices, Inc.||Epitaxy/substrate release layer|
|US7049893||Mar 30, 2004||May 23, 2006||M/A-Com, Inc.||Apparatus, methods and articles of manufacture for power amplifier control in a communication system|
|US7053713||Jun 2, 2004||May 30, 2006||Rf Micro Devices, Inc.||Multi-phase switching power supply having both voltage and current feedback loops|
|US7088183||Jul 6, 2004||Aug 8, 2006||Kabushiki Kaisha Toshiba||Bias circuit|
|US7098740||Oct 21, 2003||Aug 29, 2006||Renesas Technology Corp.||Radio frequency power amplifier and communication system|
|US7109791||Jul 9, 2004||Sep 19, 2006||Rf Micro Devices, Inc.||Tailored collector voltage to minimize variation in AM to PM distortion in a power amplifier|
|US7132891||Aug 17, 2004||Nov 7, 2006||Rf Micro Devices, Inc.||Power amplifier control using a switching power supply|
|US7148557||Aug 29, 2003||Dec 12, 2006||Matsushita Electric Industrial Co., Ltd.||Bipolar transistor and method for fabricating the same|
|US7151363||Jun 8, 2004||Dec 19, 2006||Rf Micro Devices, Inc.||High PSRR, fast settle time voltage regulator|
|US7154336||Oct 12, 2004||Dec 26, 2006||Matsushita Electric Industrial Co., Ltd.||High-frequency power amplifier|
|US7154339||May 19, 2003||Dec 26, 2006||Nxp B.V.||RF power amplifier|
|US7167054||Dec 2, 2004||Jan 23, 2007||Rf Micro Devices, Inc.||Reconfigurable power control for a mobile terminal|
|US7177370||Dec 17, 2003||Feb 13, 2007||Triquint Semiconductor, Inc.||Method and architecture for dual-mode linear and saturated power amplifier operation|
|US7190935||Sep 14, 2001||Mar 13, 2007||Rf Micro Devices, Inc.||Amplifier power detection circuitry|
|US7193459||Jun 23, 2004||Mar 20, 2007||Rf Micro Devices, Inc.||Power amplifier control technique for enhanced efficiency|
|US7227418||Jan 21, 2005||Jun 5, 2007||Matsushita Electric Industrial Co., Ltd.||Power amplifier|
|US7274748||Jun 2, 2004||Sep 25, 2007||Rf Micro Devices, Inc.||AM to FM correction system for a polar modulator|
|US7289775||Mar 6, 2003||Oct 30, 2007||Rf Micro Devices, Inc.||Method for transmit power control|
|US7301400||Jun 2, 2004||Nov 27, 2007||Rf Micro Devices, Inc.||Multi-phase switching power supply for mobile telephone applications|
|US7323728||Nov 29, 2005||Jan 29, 2008||Kabushiki Kaisha Toshiba||Semiconductor device|
|US7330071||Oct 19, 2005||Feb 12, 2008||Rf Micro Devices, Inc.||High efficiency radio frequency power amplifier having an extended dynamic range|
|US7336127||Jun 10, 2005||Feb 26, 2008||Rf Micro Devices, Inc.||Doherty amplifier configuration for a collector controlled power amplifier|
|US7345537||Sep 19, 2003||Mar 18, 2008||Triquint Semiconductor, Inc.||Linear power amplifier with multiple output power levels|
|US7382194 *||Jan 18, 2006||Jun 3, 2008||Triquint Semiconductor, Inc.||Switched distributed power amplifier|
|US7459356||Feb 23, 2006||Dec 2, 2008||Rf Micro Devices, Inc.||High voltage GaN-based transistor structure|
|US7505742||Apr 9, 2004||Mar 17, 2009||Triquint Semiconductor, Inc.||Battery life extending technique for mobile wireless applications using bias level control|
|US7529523||Aug 23, 2005||May 5, 2009||Rf Micro Devices, Inc.||N-th order curve fit for power calibration in a mobile terminal|
|US7545880||Aug 29, 2007||Jun 9, 2009||Rf Micro Devices, Inc.||Multiple polynomial digital predistortion|
|US7551686||Jun 23, 2004||Jun 23, 2009||Rf Micro Devices, Inc.||Multiple polynomial digital predistortion|
|US7566920||Jul 12, 2006||Jul 28, 2009||Panasonic Corporation||Bipolar transistor and power amplifier|
|US7598809||Nov 30, 2007||Oct 6, 2009||Silicon Storage Technology, Inc.||RF power amplifier|
|US7689182||Oct 12, 2006||Mar 30, 2010||Rf Micro Devices, Inc.||Temperature compensated bias for AM/PM improvement|
|US7801244||May 16, 2002||Sep 21, 2010||Rf Micro Devices, Inc.||Am to AM correction system for polar modulator|
|US7877060||Feb 6, 2006||Jan 25, 2011||Rf Micro Devices, Inc.||Fast calibration of AM/PM pre-distortion|
|US7960758||Apr 3, 2006||Jun 14, 2011||Panasonic Corporation||Bipolar transistor and radio frequency amplifier circuit|
|US7962108||Mar 29, 2006||Jun 14, 2011||Rf Micro Devices, Inc.||Adaptive AM/PM compensation|
|US7968391||Nov 8, 2007||Jun 28, 2011||Rf Micro Devices, Inc.||High voltage GaN-based transistor structure|
|US7991071||May 16, 2002||Aug 2, 2011||Rf Micro Devices, Inc.||AM to PM correction system for polar modulator|
|US8009762||Apr 17, 2007||Aug 30, 2011||Rf Micro Devices, Inc.||Method for calibrating a phase distortion compensated polar modulated radio frequency transmitter|
|US8072271||Oct 14, 2009||Dec 6, 2011||Rf Micro Devices, Inc.||Termination circuit based linear high efficiency radio frequency amplifier|
|US8224265||Jun 13, 2005||Jul 17, 2012||Rf Micro Devices, Inc.||Method for optimizing AM/AM and AM/PM predistortion in a mobile terminal|
|US8228122 *||May 28, 2010||Jul 24, 2012||EpicCom, Inc.||Regulator and temperature compensation bias circuit for linearized power amplifier|
|US8276259||Nov 10, 2005||Oct 2, 2012||Rf Micro Devices, Inc.||Method of constructing a differential inductor|
|US8319558||Oct 14, 2009||Nov 27, 2012||Rf Micro Devices, Inc.||Bias-based linear high efficiency radio frequency amplifier|
|US8489042||Oct 8, 2010||Jul 16, 2013||Rf Micro Devices, Inc.||Polar feedback linearization|
|US8854144 *||Sep 14, 2012||Oct 7, 2014||General Atomics||High voltage amplifiers and methods|
|US8988097||Jun 10, 2013||Mar 24, 2015||Rf Micro Devices, Inc.||Method for on-wafer high voltage testing of semiconductor devices|
|US9070761||Aug 14, 2013||Jun 30, 2015||Rf Micro Devices, Inc.||Field effect transistor (FET) having fingers with rippled edges|
|US9093420||Mar 12, 2013||Jul 28, 2015||Rf Micro Devices, Inc.||Methods for fabricating high voltage field effect transistor finger terminations|
|US9093972 *||Nov 25, 2010||Jul 28, 2015||Eads Deutschland Gmbh||Limiting circuit|
|US9124221||Jul 16, 2013||Sep 1, 2015||Rf Micro Devices, Inc.||Wide bandwidth radio frequency amplier having dual gate transistors|
|US9129802||Aug 22, 2013||Sep 8, 2015||Rf Micro Devices, Inc.||Lateral semiconductor device with vertical breakdown region|
|US9136341||Mar 12, 2013||Sep 15, 2015||Rf Micro Devices, Inc.||High voltage field effect transistor finger terminations|
|US9142620||Jun 5, 2013||Sep 22, 2015||Rf Micro Devices, Inc.||Power device packaging having backmetals couple the plurality of bond pads to the die backside|
|US9147632||Aug 23, 2013||Sep 29, 2015||Rf Micro Devices, Inc.||Semiconductor device having improved heat dissipation|
|US9202874||Aug 2, 2013||Dec 1, 2015||Rf Micro Devices, Inc.||Gallium nitride (GaN) device with leakage current-based over-voltage protection|
|US20030054778 *||Sep 14, 2001||Mar 20, 2003||Hecht James Burr||Amplifier power detection circuitry|
|US20030054780 *||Oct 23, 2002||Mar 20, 2003||Hitachi, Ltd.||High frequency power amplifying circuit, and mobile communication apparatus using it|
|US20030102924 *||Mar 30, 2001||Jun 5, 2003||Hidetoshi Matsumoto||Power amplifier module|
|US20030155977 *||Dec 13, 2002||Aug 21, 2003||Johnson Douglas M.||Gain block with stable internal bias from low-voltage power supply|
|US20030215025 *||May 16, 2002||Nov 20, 2003||Hietala Alexander Wayne||AM to PM correction system for polar modulator|
|US20030215026 *||May 16, 2002||Nov 20, 2003||Hietala Alexander Wayne||AM to AM correction system for polar modulator|
|US20040041235 *||Aug 29, 2003||Mar 4, 2004||Matsushita Electric Industrial Co. Ltd.||Bipolar transistor and method for fabricating the same|
|US20040070454 *||Jun 27, 2003||Apr 15, 2004||Triquint Semiconductor, Inc.||Continuous bias circuit and method for an amplifier|
|US20040072554 *||Sep 11, 2003||Apr 15, 2004||Triquint Semiconductor, Inc.||Automatic-bias amplifier circuit|
|US20040108901 *||Sep 19, 2003||Jun 10, 2004||Triquint Semiconductor, Inc.||Linear power amplifier with multiple output power levels|
|US20040113699 *||Oct 21, 2003||Jun 17, 2004||Renesas Technology Corp.||Radio frequency power amplifier and communication system|
|US20040145417 *||Jan 9, 2004||Jul 29, 2004||Hidetoshi Matsumoto||Power amplifier module|
|US20040150429 *||Jan 22, 2004||Aug 5, 2004||Renesas Technology Corp.||Semiconductor device with bipolar transistor device|
|US20040164804 *||Aug 7, 2003||Aug 26, 2004||Jin Wook Cho||Power amplifier with distributed capacitor|
|US20040183511 *||Mar 17, 2003||Sep 23, 2004||Rf Micro Devices, Inc.||DC-DC converter with reduced electromagnetic interference|
|US20040189396 *||Mar 27, 2003||Sep 30, 2004||Shuyun Zhang||Amplifier circuit|
|US20040201421 *||Mar 30, 2004||Oct 14, 2004||M/A-Com, Inc.||Apparatus, methods and articles of manufacture for power amplifier control in a communication system|
|US20050062541 *||Jul 6, 2004||Mar 24, 2005||Yasuhiko Kuriyama||Bias circuit|
|US20050077964 *||Oct 12, 2004||Apr 14, 2005||Matsushita Electric Industrial Co., Ltd.||High-frequency power amplifier|
|US20050088236 *||Oct 29, 2004||Apr 28, 2005||Hidetoshi Matsumoto||Power amplifier module|
|US20050088237 *||Oct 22, 2003||Apr 28, 2005||Rf Micro Devices, Inc.||Temperature compensated power amplifier power control|
|US20050135502 *||Dec 17, 2003||Jun 23, 2005||Triquint Semiconductor, Inc.||Method and architecture for dual-mode linear and saturated power amplifier operation|
|US20050176209 *||Feb 14, 2003||Aug 11, 2005||Rf Micro Devices, Inc.||Embedded passive components|
|US20050218990 *||Jan 21, 2005||Oct 6, 2005||Matsushita Electric Industrial Co., Ltd.||Power amplifier|
|US20050253656 *||May 19, 2003||Nov 17, 2005||Niels Kramer||Rf power amplifier|
|US20060044067 *||Aug 30, 2005||Mar 2, 2006||Matsushita Electric Industrial Co., Ltd.||High-frequency power amplifier|
|US20060054932 *||Sep 13, 2005||Mar 16, 2006||Matsushita Electric Industrial Co., Ltd.||Semiconductor device, high-frequency amplifier and personal digital assistant|
|US20060131608 *||Nov 29, 2005||Jun 22, 2006||Kabushiki Kaisha Toshiba||Semiconductor device|
|US20060132241 *||Oct 8, 2004||Jun 22, 2006||Katsuhiko Kawashima||Transistor integrated circuit device and manufacturing method thereof|
|US20060176117 *||Sep 28, 2005||Aug 10, 2006||Matsushita Electric Industrial Co., Ltd.||Semiconductor integrated circuit apparatus|
|US20060223484 *||Apr 3, 2006||Oct 5, 2006||Matsushita Electric Industrial Co., Ltd.||Bipolar transistor and radio frequency amplifier circuit|
|US20060255880 *||May 1, 2006||Nov 16, 2006||Hidefumi Suzaki||RF amplifier|
|US20070012949 *||Jul 12, 2006||Jan 18, 2007||Katsuhiko Kawashima||Bipolar transistor and power amplifier|
|US20070096151 *||Nov 21, 2006||May 3, 2007||Matsushita Electric Industrial Co., Ltd.||Bipolar transistor and method for fabricating the same|
|US20070139105 *||Jun 10, 2005||Jun 21, 2007||Rf Micro Devices, Inc.||Doherty amplifier configuration for a collector controlled power amplifier|
|US20070176677 *||Jan 18, 2006||Aug 2, 2007||Triquint Semiconductor, Inc.||Switched distributed power amplifier|
|US20090140814 *||Nov 30, 2007||Jun 4, 2009||Silicon Storage Technology, Inc.||Rf power amplifier|
|US20120281325 *||Nov 25, 2010||Nov 8, 2012||Eads Deutschland Gmbh||Limiting Circuit|
|US20140077884 *||Sep 14, 2012||Mar 20, 2014||General Atomics||High voltage amplifiers and methods|
|CN101053151B||Sep 28, 2005||Jan 25, 2012||株式会社村田制作所||Semiconductor device and power amplifier|
|CN103338010A *||May 28, 2013||Oct 2, 2013||苏州英诺迅科技有限公司||Circuit for improving self-heating effect of power amplifier|
|DE10297355B4 *||Oct 21, 2002||Sep 21, 2006||Infineon Technologies Ag||Breitbandhochfrequenz-Signalverstärker|
|DE112005002800B4 *||Sep 28, 2005||Jun 6, 2012||Murata Manufacturing Co., Ltd.||Hochfrequenzschaltung und Leistungsverstärker mit derselben|
|EP0954095A2 *||Apr 21, 1999||Nov 3, 1999||NEC Corporation||Power amplifier|
|EP1143609A2 *||Mar 27, 2001||Oct 10, 2001||Kabushiki Kaisha Toshiba||High frequency power amplifier having a bipolar transistor|
|EP1469592A1 *||Apr 14, 2004||Oct 20, 2004||M/A-Com, Inc.||Apparatus for and method of controlling the base bias voltage of an HBT|
|EP1548928A1 *||Oct 13, 2004||Jun 29, 2005||Matsushita Electric Industrial Co., Ltd.||High-frequency power amplifier|
|WO2002098008A2 *||May 29, 2002||Dec 5, 2002||Conexant Systems Inc||Non-linear transistor circuits with thermal stability|
|WO2003012982A2 *||Jul 29, 2002||Feb 13, 2003||Triquint Semiconductor Inc||Tuned damping circuit for power amplifier output|
|WO2003026333A1 *||Sep 10, 2002||Mar 27, 2003||Rf Micro Devices Inc||Amplifier power detection circuitry|
|WO2003098795A1 *||May 19, 2003||Nov 27, 2003||Heeres Rob M||Rf power amplifier|
|WO2004095688A2 *||Mar 18, 2004||Nov 4, 2004||Analog Devices Inc||Amplifier circuit|
|U.S. Classification||330/289, 330/296, 330/307, 330/295|
|International Classification||H03F3/19, H03F3/21, H03F1/30|
|Cooperative Classification||H03F3/19, H03F3/211, H03F2203/21178, H03F1/302|
|European Classification||H03F3/21C, H03F3/19, H03F1/30C|
|Aug 28, 2000||FPAY||Fee payment|
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|Feb 12, 2002||AS||Assignment|
|Nov 27, 2002||AS||Assignment|
|Oct 20, 2004||FPAY||Fee payment|
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|Nov 6, 2008||FPAY||Fee payment|
Year of fee payment: 12
|Mar 19, 2013||AS||Assignment|
Owner name: BANK OF AMERICA, N.A., AS ADMINISTRATIVE AGENT, TE
Free format text: NOTICE OF GRANT OF SECURITY INTEREST IN PATENTS;ASSIGNOR:RF MICRO DEVICES, INC.;REEL/FRAME:030045/0831
Effective date: 20130319
|Mar 25, 2013||AS||Assignment|
Owner name: RF MICRO DEVICES, INC., NORTH CAROLINA
Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:PRATT, WILLIAM J.;REEL/FRAME:030076/0693
Effective date: 19950523
|Mar 30, 2015||AS||Assignment|
Owner name: RF MICRO DEVICES, INC., NORTH CAROLINA
Free format text: TERMINATION AND RELEASE OF SECURITY INTEREST IN PATENTS (RECORDED 3/19/13 AT REEL/FRAME 030045/0831);ASSIGNOR:BANK OF AMERICA, N.A., AS ADMINISTRATIVE AGENT;REEL/FRAME:035334/0363
Effective date: 20150326